I've seen no aggression from the fils whatsoever, and the others I didn't observe doing any jaw-locking. The fish would appear fine, then all of a sudden they would have this lock-jaw condition. They appeared fine in other respects--aside from the stressed look of having their mouth gaping open. I think I remember this happening to one of my cacatuoides, and than also to a bitaeniata at some other point. I do remember this being discussed a good while back, but can't remember if there was any consensus on what it was, other than annoying. Zack ------------------------------------------------------------------------- This is the apistogramma mailing list, apisto@listbox.com. For instructions on how to subscribe or unsubscribe or get help, email apisto-request@listbox.com. apisto-digest@listbox.com also available. Web archives at http://lists.thekrib.com/apisto